An Interval Based Approach To Model Input Uncertainty In Discrete-event Simulation

The objective of this research is to increase the robustness of discrete-event simulation (DES) when input uncertainties associated models and parameters are present. Input uncertainties in simulation have different sources, including lack of data, conflicting information and beliefs, lack of introspection, measurement errors, and lack of information about dependency. A reliable solution is obtained from a simulation mechanism that accounts for these uncertainty components in simulation. An interval-based simulation (IBS) mechanism based on imprecise probabilities is proposed, where the statistical distribution parameters in simulation are intervals instead of precise real numbers. This approach incorporates variability and uncertainty in systems. In this research, a standard procedure to estimate interval parameters of probability distributions is developed based on the measurement of simulation robustness. New mechanisms based on the inverse transform to generate interval random variates are proposed. A generic approach to specify the required replication length to achieve a desired level of robustness is derived. Furthermore, three simulation clock advancement approaches in the interval-based simulation are investigated. A library of Java-based IBS toolkits that simulates queueing systems is developed to demonstrate the new proposed reliable simulation. New interval statistics for interval data analysis are proposed to support decision making. To assess the performance of the IBS, we developed an interval-based metamodel for automated material handling systems, which generates interval performance measures that are more reliable and computationally more efficient than traditional DES simulation results

Instruction fusion and vector processor virtualization for higher throughput simultaneous multithreaded processors

The utilization wall, caused by the breakdown of threshold voltage scaling, hinders performance gains for new generation microprocessors. To alleviate its impact, an instruction fusion technique is first proposed for multiscalar and many-core processors. With instruction fusion, similar copies of an instruction to be run on multiple pipelines or cores are merged into a single copy for simultaneous execution. Instruction fusion applied to vector code enables the processor to idle early pipeline stages and instruction caches at various times during program implementation with minimum performance degradation, while reducing the program size and the required instruction memory bandwidth. Instruction fusion is applied to a MIPS-based dual-core that resembles an ideal multiscalar of degree two. Benchmarking using an FPGA prototype shows a 6-11% reduction in dynamic power dissipation as well as a 17-45% decrease in code size with frequent performance improvements due to higher instruction cache hit rates. The second part of this dissertation deals with vector processors (VPs) which are commonly assigned exclusively to a single thread/core, and are not often performance and energy efficient due to mismatches with the vector needs of individual applications. An easy-to-implement VP virtualization technology is presented to improve the VP in terms of utilization and energy efficiency. The proposed VP virtualization technology, when applied, improves aggregate VP utilization by enabling simultaneous execution of multiple threads of similar or disparate vector lengths on a multithreaded VP. With a vector register file (VRF) virtualization technique invented to dynamically allocate physical vector registers to threads, the virtualization approach improves programmer productivity by providing at run time a distinct physical register name space to each competing thread, thus eliminating the need to solve register name conflicts statically. The virtualization technique is applied to a multithreaded VP prototyped on an FPGA; it supports VP sharing as well as power gating for better energy efficiency. A throughput-driven scheduler is proposed to optimize the virtualized VP’s utilization in dynamic environments where diverse threads are created randomly. Simulations of various low utilization benchmarks show that, with the proposed scheduler and power gating, the virtualized VP yields a larger than 3-fold speedup while the reduction in the total energy consumption approaches 40% compared to the same VP running in the single-threaded mode. The third part of this dissertation focuses on combining the two aforementioned technologies to create an improved VP prototype that is fully virtualized to support thread fusion and dynamic lane-based power-gating (PG). The VP is capable of dynamically triggering thread fusion according to the availability of similar threads in the task queue. Once thread fusion is triggered, every vector instruction issued to the virtualized VP is interpreted as two similar instructions working in two independent virtual spaces, thus doubling the vector instruction issue rate. Based on an accurate power model of the VP prototype, two different policies are proposed to dynamically choose the optimal number of active VP lanes. With the combined effort of VP lane-based PG and thread fusion, compared to a conventional VP without the two proposed capabilities, benchmarking shows that the new prototype yields up to 33.8% energy reduction in addition to 40% runtime improvement, or up to 62.7% reduction in the product of energy and runtime

A template modeling for an assembly control : jig design

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007."September 2007."Includes bibliographical references (p. 94-95).The purpose of this thesis is to identify a solution for one of the several mechanical concerns that Varian Semiconductor Equipment is facing to achieve its goal. Managers and engineers are trying to lead Varian Semiconductor Equipment to a flow line shipment program, the intent being to eliminate the clean room area and ship all of the components of the ion implanter directly from the flow line to the customer, without the currently necessary step of a final assembly. In particular this work examines the correct alignment of the source chamber inside the terminal module prior to the final assembly of ion implantation equipment. In the flow line shipment context, the correct alignment of subassembly components becomes a critical aspect and needs to be checked before a shipment, since assembly errors or out of specification components from suppliers may lead to long delays and reworks. This last aspect cannot be ignored, since if adjustments and modifications can easily be accomplished in the flow line without conspicuous waste of time, the same cannot be said in the field, thousands miles away from the factory. Specifically, the contribution of the project is to achieve the right orientation of the source chamber in relation to the position of the feet of the terminal module, by designing a mechanical fixture. The tool has been conceived to be used directly in the terminal module flow line, in order to allow technicians to quickly perform a correct alignment and easily point out any possible misalignment due to bad components or assembly errors. The main components of the fixture are the jig that checks the position of the insulators and a vertical target where two lasers shoot to align the source chamber.by Matteo Liscaio.M.Eng

Intelligent production control for time-constrained complex job shops

Im Zuge der zunehmenden Komplexität der Produktion wird der Wunsch nach einer intelligenten Steuerung der Abläufe in der Fertigung immer größer. Sogenannte Complex Job Shops bezeichnen dabei die komplexesten Produktionsumgebungen, die deshalb ein hohes Maß an Agilität in der Steuerung erfordern. Unter diesen Umgebungen sticht die besonders Halbleiterfertigung hervor, da sie alle Komplexitäten eines Complex Job-Shop vereint. Deshalb ist die operative Exzellenz der Schlüssel zum Erfolg in der Halbleiterindustrie. Diese Exzellenz hängt ganz entscheidend von einer intelligenten Produktionssteuerung ab. Ein Hauptproblem bei der Steuerung solcher Complex Job-Shops, in diesem Fall der Halbleiterfertigung, ist das Vorhandensein von Zeitbeschränkungen (sog. time-constraints), die die Transitionszeit von Produkten zwischen zwei, meist aufeinanderfolgenden, Prozessen begrenzen. Die Einhaltung dieser produktspezifischen Zeitvorgaben ist von größter Bedeutung, da Verstöße zum Verlust des betreffenden Produkts führen. Der Stand der Technik bei der Produktionssteuerung dieser Dispositionsentscheidungen, die auf die Einhaltung der Zeitvorgaben abzielen, basiert auf einer fehleranfälligen und für die Mitarbeiter belastenden manuellen Steuerung. In dieser Arbeit wird daher ein neuartiger, echtzeitdatenbasierter Ansatz zur intelligenten Steuerung der Produktionssteuerung für time-constrained Complex Job Shops vorgestellt. Unter Verwendung einer jederzeit aktuellen Replikation des realen Systems werden sowohl je ein uni-, multivariates Zeitreihenmodell als auch ein digitaler Zwilling genutzt, um Vorhersagen über die Verletzung dieser time-constraints zu erhalten. In einem zweiten Schritt wird auf der Grundlage der Erwartung von Zeitüberschreitungen die Produktionssteuerung abgeleitet und mit Echtzeitdaten anhand eines realen Halbleiterwerks implementiert. Der daraus resultierende Ansatz wird gemeinsam mit dem Stand der Technik validiert und zeigt signifikante Verbesserungen, da viele Verletzungen von time-constraints verhindert werden können. Zukünftig soll die intelligente Produktionssteuerung daher in weiteren Complex Job Shop-Umgebungen evaluiert und ausgerollt werden

Reducing Internet Latency : A Survey of Techniques and their Merit

Bob Briscoe, Anna Brunstrom, Andreas Petlund, David Hayes, David Ros, Ing-Jyh Tsang, Stein Gjessing, Gorry Fairhurst, Carsten Griwodz, Michael WelzlPeer reviewedPreprin

A template modeling for an assembly control : the source chamber alignment

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007."September 2007."Includes bibliographical references (leaves 105-106).Managers and engineers are trying to lead Varian Semiconductor Equipment to a flow line shipment program, the intent being to eliminate the clean room area and ship all of the components of the ion implanter directly from the flow line to the customer, without the currently necessary step of a final assembly prior to shipment. The purpose of the thesis is to identify a solution for one of the several mechanical concerns that the company is facing to achieve its goal; in particular this work examines the correct alignment of the source chamber inside the terminal module. In the flow line shipment context, the correct alignment of subassembly components becomes a critical aspect and needs to be checked before a shipment, since assembly errors or out of specification components from suppliers may lead to long delays and reworks. This last aspect cannot be ignored, since if adjustments and modifications can easily be accomplished in the flow line without conspicuous waste of time, the same cannot be said in the field, thousands miles away from the factory. Specifically, the contribution of the project is to achieve the right orientation of the source chamber in relation to the position of the feet of the terminal module, by designing a mechanical fixture. The tool has been conceived to be used directly in the terminal module flow line, in order to allow technicians to quickly perform a correct alignment and easily point out any possible misalignment due to bad components or assembly errors. The main components of the fixture will be the jig that checks the position of the insulators and a laser bracket in which two lasers will shoot a target to align the source chamber.by Simone Guerra.M.Eng

The NA62 VetoCounter sub-detector readout system upgrade and performance evaluation.

NA62 è un medio esperimento di fisica delle particelle ubicato alla North Area beam facility al CERN. L'obiettivo principale di NA62 è lo studio del decadimento kaonico ultra raro PNN (K + → π + ν ν̄). A causa del suo branching ratio estremamente ridotto risulta fondamentale avere un efficace sistema di vetoing per muoni e fotoni; la maggior parte dei rivelatori di NA62 sono appunto dedicati a questo scopo. Nel 2020 un nuovo subrivelatore chiamato Veto Counter è stato installato. Questo dispositivo è progettato per ridurre i contributi spuri causati dalle interazioni secondarie del fascio con gli elementi della linea. NA62 utilizza attualmente la scheda TEL62 come spina dorsale del suo sistema di acquisizione dati (DAQ), questa è una versione altamente migliorata e aggiornata della scheda TELL1 originariamente sviluppata per LHCb. In seguito ai crescenti requisiti dell'esperimento, i limiti del sistema di lettura basato su TEL62 sono sempre più evidenti. Tra questi, la scarsa resistenza alle radiazioni e i limiti sulla velocità di lettura dei moduli di conversione tempo-digitale (TDC) utilizzati. Si prevede quindi un aggiornamento del sistema di lettura utilizzando un nuovo TDC progettato per interfacciarsi con la piattaforma FELIX, sviluppata per l'esperimento ATLAS. Il Veto Counter è dotato di un doppio sistema di acquisizione TEL62 e FELIX e viene utilizzato come banco di prova per la valutazione del nuovo readout. In questo lavoro vengono studiate le prestazioni del Veto Counter e viene eseguito un confronto tra il sistema basato su TEL62 e quello basato su FELIX. Inoltre, viene progettato e testato sulla piattaforma del Veto Counter un sistema di controllo per il TDC FELIX. Nel Capitolo 1 verrà fornita un'introduzione generale sulla fisica studiata a NA62. Per raggiungere i suoi obiettivi sperimentali, NA62 richiede un progetto specifico; nel Capitolo 2 verranno dunque discusse le scelte progettuali più rilevanti per quanto riguarda il trigger e la struttura sperimentale. Nel Capitolo 3 viene fornita una panoramica dei principali sub-rilevatori, mentre nel Capitolo 4 viene fornita una descrizione dell'attuale sistema di trigger e acquisizione dati di NA62. Il lavoro di aggiornamento del sistema di lettura FELIX sarà descritto in dettaglio nel capitolo 5, insieme a una descrizione delle principali limitazioni del sistema basato su TEL62. L'aggiornamento, quando completato, coinvolgerà tutti i sub-rivelatori di NA62 che attualmente utilizzano un sistema TEL62. La progettazione del software del sistema di controllo FELIX, sviluppato in questo lavoro, è descritta in dettaglio nel Capitolo 6. Il Capitolo 7 descrive invece il subrivelatore Veto Counter, banco di prova per la nuova tecnologia di lettura e dotato di un doppio sistema TEL62-FELIX. Infine, nel Capitolo 8 viene presentato lo studio delle prestazioni del Veto Counter e del suo readout. Nell'Appendice C sono inoltre presentate alcune osservazioni su un possibile utilizzo del Veto Counter per aiutare l'estrapolazione a monte delle tracce.NA62 is a medium-sized particle physics experiment located in the CERN North Area beam facility. Its main objective is to study the ultra rare kaon decay channel PNN (K + → π + ν ν̄). Given the extremely low branching ratio of the signal, muon and photon vetoing is of paramount importance and most of the subdetectors in NA62 are dedicated to this function. In 2020, a new sub-detector named Veto Counter has been installed. This device is designed to reduce the spurious contributions of secondary interactions happening within the beam line. NA62 currently uses the TEL62 digital board as the backbone of its data acquisition (DAQ) system, which is a highly improved and upgraded version of the TELL1 board originally developed for LHCb. Following the ever growing requirements of the NA62 experiment, the limitations of the TEL62-based readout are showing more and more. These include lack of radiation hardness and readout rate limitations of the aging Time to Digital converter modules used. An upgrade of the readout system using a new custom time to digital converter (TDC) in combination with the modern FELIX card developed for the ATLAS experiment is thus envisioned. The Veto Counter is equipped with a dual TEL62 and FELIX readout and is used as a test bench in the evaluation of the new readout. In this work the performance of the Veto Counter is studied and a comparison between TEL62 and FELIX readout is performed. Furthermore a control system for the newly developed FELIX TDC is designed and tested on the Veto Counter platform. A general introduction on the physics studied at NA62 will be given in Chapter 1. In order to fulfill its experimental goals NA62 requires a specific design; in Chapter 2 we will discuss the most relevant design choices regarding trigger and experimental structure. An overview of the main sub-detectors is given in Chapter 3 while in Chapter 4 a description of the current Trigger and Data Acquisition system of NA62 is given. The FELIX readout upgrade effort will be detailed in Chapter 5, together with a description of the main limitations of the TEL62 readout. This upgrade is expected to involve all the sub-detectors at NA62 currently using a TEL62 system. Software design of the FELIX control system, developed in this work is described in depth in Chapter 6. Chapter 7 will give a description of the Veto Counter subdetector; being a test bench for the new readout technology it features a dual TEL62-FELIX readout. Finally, the performance study of the Veto counter and its readout is presented in Chapter 8. As an aside, in Appendix C some observation on a possible use of the Veto Counter to aid in upstream track extrapolation are presented

An experimental rock mechanics investigation into shear discontinuities and their influence in the hydrocarbon resevoir environment

Abstract unavailable please refer to PD

Design of a kite controller for airborne wind energy

Airborne wind energy is a field of technology being developed to make use of the vast, renewable wind power resource which is above the reach of traditional wind turbines, without the need for a large tower. Much analytical research has been undertaken in recent years to better understand the problem space. However, there are relatively few working systems that demonstrate their functioning and can be compared with simulations and theory. Off-grid power systems still rely heavily on diesel generators, so devices that tap renewable energy sources with similar ease of deployment and lower cost of energy would help this sector to reduce its reliance on expensive, polluting, fossil fuels. The development of these systems is often performed by teams with business interests leaving little open access content available regarding the design process of such devices or the data that they provide. A kite control pod has been designed for the remote control of a standard kitesurfing kite and a prototype has been demonstrated stably flying such a kite on a fixed length tether. This pod and kite would be tethered to a winch and as the kite flies across the wind, the lift force generated is applied to the winch which is reeled out and electrical power generated. Once fully extended, the tether would be reeled in with the kite de-powered, using some of the generated energy, stored in a battery. This system can then be used as a test bed for the further development of a compact, autonomous, airborne wind energy system for off-grid applications